There is no universally best choice among polypropylene (PP), acrylonitrile butadiene styrene (ABS), and polycarbonate (PC). The right material depends on the part’s load, temperature, impact exposure, chemicals, appearance, compliance needs, production volume, and the exact resin grade. This guide helps B2B buyers screen the options and prepare a useful resin specification before tooling is quoted.
Quick comparison for injection-molded parts
| Material | Why buyers consider it | What to check for the actual grade |
|---|---|---|
| PP | Often considered for lower part weight, chemical exposure, fatigue, and living-hinge designs. | Dimensional shrinkage and warpage, stiffness, impact at service temperature, hinge life, color, and any food-contact or recycled-content requirements. |
| ABS | Often considered when buyers need a balance of rigidity, impact performance, and a finish that suits cosmetic housings. | Service temperature, UV and weather exposure, chemical compatibility, plating or paint requirements, and grade-specific impact results. |
| PC | Often considered for impact and heat requirements; selected grades can also provide optical clarity. | Chemical compatibility, stress cracking, moisture handling, processing window, wall thickness, and the optical requirements of the part. |
| PC/ABS | A blend may offer a different balance of heat, impact, flow, surface, and chemical performance. | Compare the exact supplier grade and test conditions. Blend performance is not a fixed midpoint between PC and ABS. |
Use this table to shortlist materials, not as a substitute for a grade datasheet. Properties vary by supplier, additives, reinforcement, color, test method, specimen, and conditioning.
When PP may fit
PP is a candidate for parts where low weight, chemical exposure, repeated flexing, or an integral hinge matters. A living hinge still depends on resin grade, hinge geometry, flow direction, gate location, and molding conditions. LyondellBasell’s polyolefin injection-molding guide discusses these design and process factors for polyolefins.
Do not choose PP only because it is described as low cost or chemically resistant. Check the chemical, temperature, load, appearance, and dimensional requirements for the specific part, then confirm the proposed grade and its supplier data.
When ABS may fit
ABS is often evaluated for rigid housings and trim where impact performance and surface appearance are both important. Paintability, plating, weather resistance, and chemical resistance depend on the specific grade and finish process. If the part will be outdoors, exposed to cleaners, or under sustained stress, put those conditions into the material review rather than relying on a family-level label.
When PC or PC/ABS may fit
PC grades are often considered when impact or heat performance is a priority; transparent grades may be appropriate when optical requirements are defined. Chemical exposure and residual stress can affect performance, so test the part in its real environment. PC/ABS blends also vary substantially: supplier catalogues list grades with different flow, low-temperature impact, heat, and chemical-resistance profiles. Compare the data for the exact grade, such as Covestro’s Bayblend PC/ABS range.
Why the resin grade matters to tooling
Shrinkage is not one fixed number for every grade in a resin family. In its current Moldflow warpage guidance, Autodesk describes shrinkage variation across part regions, through the wall thickness, and relative to material orientation; it also notes that material choice influences warpage. Use the exact grade, part geometry and agreed process assumptions for mold review rather than treating a family-level value as a universal prediction (Autodesk 2026 Moldflow warpage guidance).
Lock the intended supplier and grade before finalizing the mold assumptions. If a grade changes later, have the molder review fit, critical dimensions, process settings, and validation samples. A material change may be workable in an existing tool, but the outcome depends on the grade and part; it should not be assumed to require—or avoid—a tool change.
Processing temperatures and drying instructions also belong to the supplier’s grade-specific datasheet. Do not use a generic PP, ABS, or PC temperature range as a production setting.
What to include in a resin RFQ
- Named resin supplier and grade, or the performance targets that an alternative must meet.
- Service temperature, impact or load conditions, chemical exposure, UV/weather exposure, and expected product life.
- Appearance, transparency, color, texture, painting, plating, or other finish requirements.
- Critical dimensions, tolerances, assembly interfaces, and the measurement method for acceptance.
- Annual volume, order quantity, expected batch size, and any ramp schedule.
- Required regulatory, food-contact, flame, recycled-content, or customer-specific documentation.
- Whether substitutions are allowed, and what approval or revalidation is required before a grade changes.
Ask each supplier to identify the exact grade in the quote, attach its current technical data, list any substitute separately, and state which assumptions require sample testing. For the mold and part-design inputs, see DAYIN’s injection-molding DFM checklist and wall-thickness guide.
Frequently asked questions
Which of PP, ABS, or PC costs the least?
There is no reliable price ranking for every grade and program. Compare the quoted resin grade, part weight, cycle assumptions, scrap, secondary operations, quality requirements, and order volume. See the guide to injection-molded part cost factors.
Can a supplier switch resin after the mold is built?
Possibly, but the new grade should be reviewed against dimensions, fit, appearance, process window, and end-use requirements. Request a documented trial and approval before releasing production.
Which resin is best for a living hinge?
PP is commonly evaluated for living hinges, but hinge life depends on the grade, geometry, gate and flow arrangement, and molding conditions. Confirm the required flex cycles on representative samples.
What processing temperature should I specify?
Specify the resin grade and have the molder follow the supplier’s current processing guidance. Melt, mold, and drying conditions vary by grade and machine; they should not be selected from a generic family table.
For a project-specific material and tooling review, see DAYIN’s custom plastic injection-molding service or send the drawing and annual volume.